Artificial hand



p 1951 w. J. PHILPOTT- 2,568,299

. ARTIFICIAL HAND Fi led June 2, 1949 /NVEN7'0I? WILLIAM JAMES PHILPOTTy WM 7 AGE/VT Patented Sept. 18, 1951 ARTIFICIAL HAND William JamesPhilpott, London, England, assignor to Hugh Steeper Limited, a Britishcom- Application June 2, 1949, Serial No. 96,703 In Great Britain June4, 1948 This invention relates to artificial hands, and moreparticularly to artificial hands having a thumb which is movable towardsor away from the fingers, for gripping or carrying, and releasingobjects. In such an artificial hand the thumb is usually pivotallymounted at its base in the palm or body portion of the hand, at thedesired angle in relation to the fingers. Thus the pivotal movement ofthe thumb for opening and closing is in one plane only, and is usuallyso arranged that the thumb, when closed, touches the index finger, inthe method of operation known as front opening, although if desired sideopening, or partial side opening, could be arranged. It is desirablethat the thumb be arranged to open and close, so that when closed it mayabut other fingers, as desired by the wearer. To achieve this the thumbhas a further pivotal mounting for movement of the thumb substantiallyat right angles to the normal open and close pivotal movement referredto above. This further movement will be referred to in thisspecification and claims as traversing.

According to this invention an artificial hand is provided with a thumbpivotally mounted for open and close movement and mounted also fortraversing, wherein the thumb may be fixed in any one of a plurality ofpositions, in any of which positions it may open or close. Freedom fortraversing between positions may be given when the control of the handreaches a predetermined position.

An artificial thumb in accordance with this invention is preferably usedin an artificial hand as described in my co-pending application SerialNo. 96,701, filed June 2, 1949, in which the control is used to open thehand, which is automatically closed.

In order that the invention may be clearly understood the preferredconstruction will now be described in more detail, as an example, andwith reference to the accompanying drawings, in which- Figure 1 is aside elevation of the thumb with parts shown in sections;

Figure 2 is a section, on the line H--ll of Fi ure 1, of the operatingmechanism only, the thumb being shown diagrammatically; and

Figure 3 is a detail top plan of the hemispherical base of the thumb.

The thumb 44 is pivotally mounted as at 45 for traversing on ahemispherical base 46-, which is in turn pivotally mounted as at 9 onthe body portion, or palm, of the hand (not shown), for the usual openand close movement. The two pivots 2 Claims. (01. 312) lie substantiallyin the same plane (at right angles to the section plane in Figure l) andare disposed at right angles to each other. The lower extremity of thethumb is suitably shaped as at 68, and cut away to permit its movementon the pivot 45 about, the hemispherical base 46.

A small tube 49 is mounted longitudinally and centrally within thethumb, the tube housing a spring-pressed plunger 59, such that theplunger 5!! is urged downwardly out of the thumb, and into engagementwith the top surface of the hemispherical base 46. This surface isprovided with three spaced and aligned apertures 5!, 52 and 53, soarranged as to give three fixed positions for the thumb, by means of theplunger 50 engaging in the desired aperture. When the plunger is not soengaged, its end may slide over the surface of the base 4%, until itenters one of the apertures under the action of a spring 54, looking thethumb in one of the three positions. At each side, adjacent thetraversing pivotal mounting 45, are arranged fibrous washers 55 whichengage, with a light frictional rubbing action, fibrous bushes 56 On theinner surface of the thumb, so that the thumb does not traverse freely,but will remain in any intermediate'position between the three fixedpositions.

When it is in any position, the normal open and close movement of thethumb may take place. The apertures 5|, 52 and 53 are aligned in a row(see Figure 3), and so spaced apart that engagement of the plunger 50 inthe aperture 5I' (as in Figure 1) causes the thumb to be associated withthe index finger for open and close movement, engagement in the aperture53 giving association with the fourth finger. Engagement with the middleaperture 52 causes association in an intermediate position, say with thethird finger.

A plate 51 having an arcuate top edge is slidably and centrally disposedwithin the hemispherical base 46, the apertures 5|, 52 and 53. beingjoined by a slot 58 in which the plate 51 moves. Normally the top edgeof the plate 51 is below the outer surface of the base 46, so that itengages the lower end of the plunger 50 when the latter is in engagementwith one of the apertures, that is, with the thumb locked in one of thetraversing positions.

If the plate is moved upwards, its top edge will move the plungerupwards against the spring, so that the plunger no longer engages in anaperture, and the thumb may be traversed to another position. This stateis shownin Figures 1 and 2.

In my co-pending application referred to above an artificial handmechanism is described wherein the fingers and thumb are opened andclosed by a lever system, opening being by the control of the wearer,whilst closing is by a spring acting on the lever system. This system isconnected for the necessary movement of the thumb by a plate 21, fixedto the base of the thumb, and having a forked extension, the forkreceiving slidably a projection 28 on one of the lever system links,whereby the thumb is moved for opening and closing about the pivot 9.

A thin plate 59 is pivotally attached at 60 to one side of thethumb-moving plate 21, the thin plate 59 having a small point 6| whichnormally overlies the lower side edge of the fork, so that as theprojection 28 rides up the fork, it depresses the point 6| at one momentduring its travel in the fork. The point 6| is so shaped that theprojection 28 may easily move past it in either direction, whilst at thesame time depressing it. Since the thin plate 59 is pivotally mounted,its other end moves up when the point is depressed, and this upwardmovement is transmitted to the arcuate-edged plate 51, which is pushedupwardly to free the plunger 50 as described. This upward movement istransmitted via a pin 62 which is in contact with the lower edge of alink plate 63, to the upper edge of which is fixed the arcuate-edgedplate 51. The link plate 63 slides over the mounting pivot 9 by virtueof a slot 64.

Thus when the wearer desires to unlock the thumb for traversing toanother position, the hand control is operated, and as it opens the handto the predetermined degree, the plunger is freed and the thumb may betraversed.

Whilst the construction described is operated in conjunction with theartificial hand mechanism disclosed in my co-pending applicationreferred to above, it will be realized that other control means foroperating the arcuate-edged plate could be used.

What I claim is:

1. Artificial hand comprising a body portion. a thumb, said thumbincluding a casing, a partspherical base located within the lower partof said casing and carrying said thumb, a retractible spring-pressedplunger arranged longitudinally within said casing and above said base,said base having a plurality of spaced, aligned apertures in any ofwhich said plunger is engageable, a first pivotal mounting for mountingsaid base on said body portion for opening and closing movement of saidthumb, and a second pivotal mounting for mounting said casing on saidbase piece, the axes of said pivotal mountings being substantially atright angles, whereby said thumb may be traversed about said secondpivotal mounting and may be fixed in any one of a plurality of positionsby selective engagement of said plunger with said apertures.

2. Artificial hand comprising a body portion, a control operable by thewearer, a plurality of digits connected to said body portion and movablerelatively thereto for opening and closing said hand, one of said digitsbeing a thumb, said thumb including a casing, a part-spherical baselocated within the lower part of said casing and carrying said thumb, aretractible spring-pressed plunger arranged longitudinally within saidcasing and above said base, a mechanism in said base and said bodyportion and operated by said control, a plurality of spaced, alignedapertures in said base, said plunger being engageable in any of saidapertures, said mechanism being operable to retract said plunger fromsaid apertures, a first pivotal mounting for mounting said base on saidbody portion for opening and closing movement of said thumb, and asecond mounting for mounting said casing on said base piece, the axes ofsaid pivotal mountings being substantially at right angles, whereby saidthumb may be fixed in any one of a plurality of positions by selectiveengagement of said plunger with said apertures, traversing of said thumbabout said second pivotal mounting being permitted on retraction of saidplunger by said mechanism at a predetermined point in the operation ofsaid control.

WILLIAM JAMES PHILPOTT.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

